The present invention relates generally to a hermetic reciprocating compressor and, more particularly, to such a compressor having a lubrication system, wherein the rotation of an oil pump booster acts to increase the oil flow rate within the lubrication system.
The general prior art of hermetic compressors comprise a hermetically sealed housing having a compressor mechanism mounted therein. The compressor mechanism may include a crankcase or a cylinder block defining a compression chamber therein in which gaseous refrigerant is compressed and subsequently discharged. The pistons are reciprocated by an eccentric portion of a crankshaft rotating within a crankcase.
In prior art hermetic compressor assemblies, a lubricating system is disposed within the crankshaft. A tapered oil pickup tube is attached to one end of the crankshaft to spin within the oil in an oil sump. The tube rotation will impart a spinning motion to the oil within the tube, due to the viscous friction between the oil and the pickup tube, thereby pumping the oil up the axial oil passageway to other parts of the lubricating system.
One prior art compressor, as shown in U.S. Pat. No. 3,572,978, includes an axial oil passageway 21 disposed within the crankshaft having a radial oil passageway 29. This compressor includes a rotary pump to pump oil up into axial oil passageway 21.
Another prior art compressor, as shown in U.S. Pat. No. 2,500,751 includes an axial oil passageway 74 through the crankshaft to communicate oil to the top part of the compressor. Axial oil passageway 74 included intermediate ducts to help lubricate bearing surfaces.
A disadvantage of prior lubrication system designs is that at times the oil flow within a system is insufficient to adequately lubricate the bearings and other moving parts of the compressor.
Another disadvantage of prior lubrication designs is that oil escaping from the lubrication system may be mixed with compressed refrigerant by turbulence within the compressor thereby increasing the amount of entrained oil within the refrigerant and correspondingly reducing the amount of oil within the compressor, where it is needed. Oil suspended within the compressor refrigerant may reduce the refrigerant's ability to transfer heat.